1. Field of the Invention
This invention relates generally to a universal garage door opener and, more particularly, to a universal garage door opener adaptable to be programmed by a wide range of varying commercial garage door openers.
2. Discussion of the Related Art
As is well known, garage door openers are available that include a transmitter that transmits an encoded radio frequency (RF) signal to be received by a receiver associated with a garage door to remotely open and close the door. Universal garage door openers (UGDO) that are selectively programmable to open and close a wide-range of garage doors equipped with a conventional garage door opener are becoming increasingly popular in connection with modern day vehicles. UGDOs are generally powered by a vehicle electrical system, and are strategically located on the vehicle for convenience and aesthetic purposes. Because there are many different types of conventional garage door openers that use various types of frequency transmission schemes, an effective UGDO must be able to be programmed by the various garage door openers to be desirable in the marketplace. Thus, a UGDO will include receiver circuitry that is responsive to the transmission signal from the conventional garage door opener, and decoder circuitry that decodes and demodulates carrier wave information so that the UGDO can recreate the transmission signal for subsequent use.
The different commercially available conventional garage door openers incorporate different carrier wave modulation techniques to transmit the encoded data from the remote transmitter to the receiver. For example, the well known Stanley and Chamberlain brand garage door openers utilize a pulse code modulation (PWM) scheme transmitted at a relatively low frequency in which the carrier wave is modulated by varying the pulse widths of the signal. The well known Genie brand garage door openers also use PWM where the modulation is frequency shift keyed (FSK) at a relatively high frequency in which data is distinguished by changes in the frequency of the modulation on the carrier wave. In order to be effective, the UGDO must be able to recognize all of the different types of modulation at the different frequencies, and recreate the signals.
U.S. Pat. Nos. 5,442,340 and 5,479,155, both issued to Dykema, disclose UGDO systems that are applicable to be programmed by the well known commercially available garage door openers. Because UGDOs transmit RF signals, they are subject to FCC regulations. The FCC regulations specify a certain maximum field strength at a first frequency limit, another maximum field strength at a second frequency limit, and a linear extrapolation of maximum field strength values between the two frequency limits. Because the Chamberlain and Stanley brand garage door openers operate at a relatively low frequency, and the Genie brand operates at a relatively high frequency , the relative maximum field strength useable under the FCC regulations for the two different transmissions are significantly different. Therefore, the Dykema UGDO incorporates a controllable attenuation circuit to automatically adjust the field strength of the transmitted signal based upon the frequency and duty cycle of the transmitted signal.
Because the Dykema UGDO systems at least incorporate an attenuation circuit to maximize the field strength output at the different frequencies, significant added expense in the attenuation circuitry is required to produce these types UGDOs. Therefore, there is room for improvement in these types of systems that would minimize cost, size, etc.
It is an object of the present invention to provide a universal garage door opener (UGDO) that can be trained by a wide variety of different garage door openers to recreate their transmission signals, and minimize cost, complexity and size when compared with known UGDOs.